We propose: 1. To identify the proteins from HeLa ribosomes that are methylated by two-dimensional polyacrylamide gel electrophoresis. 2. To study the extent of methylation during the cell cycle using a synchronized HeLa culture. 3. To continue our effect on the study of the function of methylation of E. coli ribosomes by reconstituting ribosomes that are deficient in methylation. Any functional abberation associated with the methylation will be investigated. 4. To isolate and analyze mutants which are deficient in methylation of ribosomal proteins. BIBLIOGRAPHIC REFERENCES: Chang, F.N., Cohen, L.B., Navickas, I.J., and Chang, C.N., Purification and Properties of a Ribosomal Protein Methylase from E. coli Q13. Biochemistry, 14, 4994-4998 (1975). Chang, F.N., Navickas, I.J., Chang, C.N., and Dancis, B.M.; Methylation of Ribosomal Proteins in HeLa Cell. Archives of Biochemistry and Biophysics, in press (1976).